The present invention relates generally to equipment employed in the performance of angioplasty procedures including use within percutaneous transluminal coronary angioplasty (PTCA) systems and more particularly, to a check valve manifold assembly which interconnects a perfusion pump to a PTCA catheter or the like.
The use of inflatable balloon, or dilation, catheters in the treatment of coronary conditions is widespread. Catheters are used for a number of medical purposes, such as injecting radiopaque fluids into patient's body to perform an angiogram to locate blockage of arteries or other body vessels and expanding against such blockages to open them. Balloon catheters are used in expanding a blockage, commonly referred to as a stenosis, which is a narrowing or stricture of an artery or other body vessel.
In PTCA, a guide catheter is introduced into the artery of the patient and guided through the artery until the distal tip of the catheter is in the desired location of the coronary artery near the stenosis. A dilation catheter which has an inflatable balloon affixed to its distal end is then introduced along the guide catheter and advanced into the patient until the balloon end is located at the stenosis. Once located, the balloon is inflated so that it expands against the artery walls, thereby expanding, or dilating, the artery and compressing the stenosis This expansion often removes all of or a significant portion of the blockage. The balloon may be inflated against the arterial walls for only one specific time or it may be repeatedly inflated and deflated in a cycle matching the heartbeat of the patient.
Once the artery is expanded, the balloon is deflated and the balloon and guide catheters are removed so that blood may again flow through the artery. The literature describes a restenosis rate of about 15-30% which occurs in PTCA. Restenosis describes the situation where the arterial wall is expanded by the balloon and the arterial blockage is opened, but the arterial wall contracts and adopts its original, restricted state some time after the balloon is deflated and removed. There exists a belief that this restenosis rate can be lowered if longer inflation times are used during balloon catheterization procedures.
Longer balloon inflation times may be accompanied by a significant disadvantage: ischemia of the cardiac muscles. Ischemia is a local, or temporary, deficiency of oxygen in an area of the body caused by an obstruction in the blood vessel which supplies blood to that area. Because of the stenosis, the body parts or areas distal of the stenosis may already be in jeopardy.
In order to prevent ischemia, efforts have been made to develop coronary angioplasty catheters which are perfusion catheters; that is, they permit the flow of blood across or through the angioplasty balloon during inflation thereof. The perfusion of blood through a balloon catheter may be accomplished in several ways. The balloon may have one or more dedicated passages formed therein which define flow channels extending through the balloon from one end to the other and which permit the passage of blood through/across the balloon. A balloon catheter may also have a multi-lumen catheter in which one of the lumens serves exclusively as a passage to carry blood through the inflated balloon area.
Whatever the perfusion procedure and catheter structure, the blood preferably should be passed through the inflated balloon area at a specific flow rate to avoid ischemia, such as 60 cc per minute. This flow rate may be affected by certain variables, such as the diameter of the perfusion lumen which carries the blood. Because of the generally minute diameters of lumens used in PCTA procedures, an external or extracorporeal pump is commonly used to assist in the perfusion procedure, rather than rely upon the patient's heart to pump blood through the inflated balloon area. The extracorporeal pump receives blood from the patient and circulates it through the catheter and past the distal end of the balloon. These pumps may either be hand-operated syringes or conventionally powered pumps. Where syringes are used as the perfusion pumps, it is desirable to ensure continuous circulation of the blood, by the use of dual syringes connected such that as one syringe pumps blood into the patient through the balloon catheter, the other syringe draws blood from the patient into the pumping chamber and remains in a ready condition.
It is therefore desirable to provide a means for interconnecting perfusion pumps with a PCTA catheter and directing the flow of body fluids therefrom. It is especially desirable that such a means be compact and reliable and resistant to the high pumping pressures associated with perfusion.
Some extracorporeal manifolds exist, such as that described in U.S. Pat. No. 4,447,230 issued May 8, 1984. This manifold is used in association with intravenous administration of fluids and has a plurality of inlet ports arranged in an in-line fashion along a common axis in the form of tee-shaped members interconnected together. Each inlet port includes a check valve which permits one way flow of the fluids from a bag into the manifold, catheter and patient. In such an assembly, the ports and associated valves are designed for low pressures because they receive their fluids from solution bags in which the flow for intravenous administration is promoted by gravity rather than by an active pumping means.
Accordingly, it is an object of the present invention to provide an extracorporeal valve manifold assembly to use in PTCA procedures which manifold is resistant to high pumping pressures, is compact and permits interconnection of one or more perfusion pumps with a perfusion catheter and a supply catheter.
Another object of the present invention is to provide a check valve manifold assembly which is suitable for use in PCTA systems and which interconnects multiple perfusion pumps with a PCTA catheter and the patient.
Another object of the present invention is to provide a unique compact valve manifold assembly having a fluid passage which directs flow between an inlet and outlet, the assembly having a plurality of valves arranged in a housing, the fluid passage interconnecting the inlet and outlet with multiple pumping ports, each of the pumping ports having a check valve associated therewith capable of resisting high perfusion pumping pressures, in which the check valves are arranged so as to operate reliably regardless of whether blood is being perfused or aspirated.
The present invention accomplishes these objects by providing a compact valve manifold assembly having multiple valves in fluid communication with multiple ports of the manifold. These ports include a manifold inlet, a manifold outlet and one or more pump ports which are connected to multiple perfusion pumps. Two syringes may be used as perfusion pumps which are preferably synchronized so that when one of the two syringes is withdrawing, or aspirating, blood from a patient, the other syringe is pumping, or perfusing it back into the patient through the perfusion catheter to the distal end of the inflation balloon. The manifold includes a fluid passage in communicating with the inlet, outlet and pumping ports and having a plurality of check valves. The check valves may be located at equal distances within the fluid passage of the assembly so as to provide distinct flowpaths, or subpassageways with equal flow resistance so that no single flowpath has a pressure drop greater than the other. Additional ports may be provided in the assembly which communicate with the fluid passage to enable connection to the assembly of exterior fluid pressure actuated devices, such as pressure gauges and relief valves.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.